A casting is a metal object obtained by pouring molten metal into a mould and solidifying it. The process of casting is fundamental to mechanical engineering; it is one of the basic shape producing processes. In the casting process, material (a metal or its alloy) is melted by heating it to the desired temperature. It is then treated chemically - maybe by adding some other metals and chemicals - to modify its properties. The molten material is then poured into a mould and then allowed to solidify. The most common material used for casting is iron, steel, copper and aluminium. The most popular casting processes include sand casting, die casting, centrifugal casting and investment casting. Casting allows mass production of complex and very large parts, and shaping of metals that are difficult to machine. Like plastic injection moulding, casting is one of the most versatile processes for shaping metals, and India and China are two leading countries where foundries manufacture end products that Europe and Americas require.
Challenges and Castability Assessment
Whilecasting is a ubiquitous manufacturing process, it is extremely difficult to achieve high precision and quality. Most metals shrink when cooled from the liquid state, depending upon the coefficient of expansion. The challenges multiply with alloys. With so many different metals and their alloys available today, choosing the right material is challenging. Castability assessment refers to the evaluation and analysis of a material's or alloy's ability to be successfully cast into a specific shape using a particular casting process. The goal of castability assessment is to understand how well a material can flow into the intricacies of a mould and how it behaves during the casting process. This evaluation is crucial in the design and manufacturing of cast components, as it helps ensure the production of high-quality and defect-free castings. Key factors considered in castability assessment include fluidity of the molten metal, how much it shrinks while cooling, solidification characteristics, microstructure and grain size, ease of machining, etc. Meeting dimensional requirements is another challenge, especially in sand casting. Voids are caused by contraction of the metal during cooling. While voids are inner cavities, blowholes are void on surface of casting. They are caused by excessive gas entrapment or due to lack of adequate venting. Casting challenges also include hot tears which are nothing but inter crystalline failure in casting that occurs at a high temperature. Hot tears are caused by large differences in section thickness, abrupt changes in section thickness, or too many branching sections. Design engineers also need to tackle the challenge of incomplete fusion of two molten metal flows that meet inside the mould from opposite directions (called 'cold shut' in foundry parlance). If the molten material is not heated to the correct temperature, it solidifies without occupying the complete mould, resulting in incomplete castings.Most of the casting defects occur during pouring and solidification. From an engineering point of view, there are two stages of solidification: nucleation and growth. Nucleation is the process whereby stable particles or grains form as the molten liquid metal begins to cool. Each nucleation event produces a grain. The grain growth occurs as the heat of fusion is extracted from the liquid. Faster cooling rates generally produce finer grain sizes.Improper cooling of castings also results in development of stress, and the resulting strains or deformations depend on the mechanical properties of the casting material and the casting method. Stresses also develop due to non-uniform cooling of the casting. They can be particularly severe during steel casting due to the high pouring temperature of steel (relative to ambient) and the presence of geometric complexity (different section thicknesses, risers, etc.).
Castings Simulation with Altair Inspire Cast
As we have seen, the process of achieving a perfect cast is quite challenging and demands proper knowledge of metallurgy and engineering. The bigger the part, or greater the complexity, the more difficult it is to cast it properly. With the rise in simulation software, especially one that is based on finite element analysis (FEA), it is now possible for foundries to improve the quality of their castings.
Altair Inspire Cast is a comprehensive casting simulation software designed to enhance the efficiency and quality of metal casting processes. As part of the Altair Inspire platform, this tool offers a range of features to aid engineers and designers in optimizing the casting process from initial design to final production.
The software's primary utility lies in its ability to simulate the entire casting process, providing insights into critical stages such as filling, solidification, and cooling. By accurately predicting and visualizing potential defects like porosity, shrinkage, and gas entrapment, Altair Inspire Cast empowers users to make informed decisions to improve casting quality.
Mould design optimization is a key aspect of the software, allowing users to refine mould geometries to enhance the flow of molten metal, reduce turbulence, and minimize the risk of defects. The interactive visualization of simulation results enables users to identify critical areas that may require adjustments, leading to more efficient and precise designs.
Altair Inspire Cast supports the optimization of process parameters, including pouring temperature, cooling rates, and mould material. This capability enables users to experiment with different scenarios, ultimately improving the overall quality of the casting while minimizing the likelihood of defects.
The software's material database provides a diverse range of materials and alloys, allowing users to choose the most suitable options for their casting simulations. This flexibility contributes to the accuracy and relevance of the simulations to real-world manufacturing scenarios.
Altair Inspire Cast is not only focused on simulation but is part of a broader platform that includes generative design capabilities. This integration allows users to explore innovative designs that are not only optimized for performance but also take manufacturability into account.
In summary, Altair Inspire Cast serves as a powerful tool in the casting industry, offering casting simulation capabilities, mould design optimization, process parameter tuning, and seamless integration with other design tools. It is a valuable resource for industries such as automotive and aerospace, where casting plays a significant role in component manufacturing, helping to reduce costs and improve the overall quality of castings.
The casting industry in India is renowned for good quality at a reasonable price. Good casting simulation software allows manufacturers to simulate the entire casting process – right from selection of the material to the final product. For those aspiring to export precision castings, Altair Inspire Cast is an indispensible tool in order to maintain highest industry standards and improve quality of their castings.